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ASK THE PROFESSOR FORUM

Course Documents

Chapter 1 - Intro

Chapter 2 - Methods for Describing Sets of Data

Chapter 3 - Probability

Chapter 4 - Discrete Random Variables

Chapter 5 - Normal Random Variables

Chapter 6 - Sampling Distributions

Chapter 7 - Confidence Intervals

Chapter 8 - Tests of Hypothesis: One Sample

Chapter 9 - Confidence Intervals and Hypothesis Tests: Two Samples

Sample Exam I: Chapters 1 & 2

Sample Exam II: Chapters 3 & 4

Sample Exam III: Chapters 5 & 6

Sample Exam IV: Chapters 7 & 8

Ask the Professor Forum

I am reviewing each section before taking the practice exam and I am doing all of the practice problems provided on this website. I am having some trouble solving number 2 from the "NOW YOU TRY IT" for section 2.6.
(2. In July of 2011, the average age of cars on the road in the US was a record high of 11.1 years old. The standard deviation of car ages was 3.2 years old. If nothing is known about the shape of the distribution, give an interval of car ages that will contain the ages of at least 88.9% of car ages.) I would appreciate it if you could help me!!!!!!!! Thanks,

Posted to STATS 1 on Tuesday, January 28, 2014   Replies: 1


Professor Mcguckian
01/28/2014
6:31 PM EST

Hi Ruby,

I have created a video that explains how to solve this problem. Watch it, and let me know if you still have questions.

Professor McGuckian

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